task instance doc confusing

[simonbaker]

The following from the doc is confusing. It seems both a signalling task and a blocking task cannot leave the node until completed. What is the difference? Are the terms blocking and signalling just descriptive and the actual behavior defined by the six signal-properties (last, last-wait, first, first-wait, unsynchronized, never)?

11.2.2. Task instances and graph execution
Task instances are the items in an actor's tasklist. Task instances can be signalling. A signalling task instance is a task instance that, when completed, can send a signal to its token to continue the process execution. Task instances can be blocking, meaning that the related token (=path of execution) is not allowed to leave the task-node before the task instance is completed. By default task instances are signalling and non-blocking.

[undergoth]

As i understood, signaling and blocking are opposite operations, i mean, blocking happens when the token can't live the node. If the task isn't finished yet the token is still in that node so it's blocked.
If you signal the token will leave the node.

Sorry if my explanation hasn't help you at all .

[holly77]

A task with blocking set to true will throw an Exception, if you try to propagate the execution over a task, that still has open TaskInstances.
So the flag is there, to be able to make sure, that all of the TaskInstances of a task are finished.
The signalling flag is just there to indicate whether the TaskNode will signal the Token at all (true) or not (false), if e.g. all taks are finished, and is completely independent from the blocking flag.

Hint: read section 18.4.24. about tasks in the reference manual!

[simonbaker]

Thanks, those do help.